Articles of footwear and shoe soles for midfoot impact region

ABSTRACT

A shoe sole for an article of footwear is described herein. The shoe sole extends in a longitudinal direction from a heel region, through a midfoot region, to a forefoot region. The sole includes a midsole and an outsole. The midsole has an upper surface for attachment to at least one of an insole and a shoe upper, and a lower surface disposed opposite the upper surface. The midsole includes a forefoot cushioning element, a midfoot cushioning element, and a heel cushioning element. The outsole is disposed along the lower surface of the midsole and defines a ground-contacting surface of the sole. The sole has an upwardly convex bottom profile such that an impact region of the sole is defined within the midfoot region, and the midfoot cushioning element is disposed within the midfoot region and directly above the impact region of the sole.

FIELD

The field relates generally to articles of footwear and, more specifically, to shoe soles for use in articles of footwear designed for a midfoot impact region.

BACKGROUND

Articles of footwear, such as shoes, generally include a shoe sole and an upper affixed to the shoe sole which surrounds a foot resting on the sole. Some known shoe soles are designed to provide a rolling action on a user's foot, and tend to have a destabilizing effect, requiring a more active or “dynamic” response from the user's muscular and skeletal systems as compared to passive walking or running. Active walking, as compared to passive walking, provides numerous benefits, including training muscles that are typically neglected in passive walking, improving posture and gait pattern, and alleviating back, hip, leg, and foot ailments as well as joint, muscle, ligament, and tendon injuries.

Some known shoe soles are designed to provide a rolling action during walking, and generally include a relatively soft material in the heel region of the shoe sole. However, shoe soles designed for walking may provide less than optimal rolling action for running, as well as less than optimal cushioning and support for running.

Additionally, some known shoe soles designed for running include a soft element located in the heel region of the sole. For example, U.S. Pat. No. 6,341,432 to Muller, issued Jan. 29, 2002, the entire disclosure of which is hereby incorporated by reference, describes a shoe sole having a soft material disposed in a recess of the shoe sole in a heel area of the sole. However, the outer sole of the shoe has a relatively flat contour, and thus promotes an impact region along the heel of the sole. As a result, the shoe sole may provide less than optimal cushioning and support for runners having a midfoot strike.

Accordingly, a need exists for a shoe sole designed to provide a dynamic, rolling action during running.

This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

BRIEF SUMMARY

In one aspect, a shoe sole for an article of footwear is provided. The sole extends in a longitudinal direction from a heel region, through a midfoot region, to a forefoot region. The sole includes a midsole and an outsole. The midsole has an upper surface for attachment to at least one of an insole and a shoe upper, and a lower surface disposed opposite the upper surface. The midsole includes a forefoot cushioning element, a midfoot cushioning element, and a heel cushioning element. The outsole is disposed along the lower surface of the midsole and defines a ground-contacting surface of the sole. The sole has an upwardly convex bottom profile such that an impact region of the sole is defined within the midfoot region, and the midfoot cushioning element is disposed within the midfoot region and directly above the impact region of the sole.

In another aspect, a shoe sole for an article of footwear is provided. The sole extends in a longitudinal direction from a heel region, through a midfoot region, to a forefoot region. The sole includes a midsole and an outsole. The midsole has an upper surface for attachment to at least one of an insole and a shoe upper, and a lower surface disposed opposite the upper surface. The midsole includes a forefoot cushioning element, a midfoot cushioning element, and a heel cushioning element. The outsole is disposed along the lower surface of the midsole, and defines a ground-contacting surface of the sole. The sole has an upwardly convex bottom profile such that an impact region of the sole is defined within the midfoot region. The midsole has a first hardness in the forefoot region, a second hardness in the heel region less than the first hardness, and a third hardness in the midfoot region above the impact region less than both the first hardness and the second hardness.

In yet another aspect, a shoe sole for an article of footwear is provided. The sole extends in a longitudinal direction from a heel region, through a midfoot region, to a forefoot region. The sole includes a midsole and an outsole. The midsole has an upper surface for attachment to at least one of an insole and a shoe upper, and a lower surface disposed opposite the upper surface. The outsole is disposed along the lower surface of the midsole, and defines a ground-contacting surface of the sole. The sole has an upwardly convex bottom profile such that an impact region of the sole is defined within the midfoot region. The outsole has a relatively stiff construction along the midfoot region to form a pivot axis within the impact region about which the heel region and the forefoot region pivot. The heel region curves upward from the midfoot region and has a radius of curvature of between 390 millimeters and about 450 millimeters. The forefoot region extends upward from the midfoot region, and has a radius of curvature of between 360 millimeters and about 420 millimeters.

Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described aspects, alone or in any combination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral side view of an article of footwear including an example embodiment of a shoe sole;

FIG. 2 is a medial side view of the shoe sole of FIG. 1;

FIG. 3 is a bottom plan view of the shoe sole of FIG. 1;

FIG. 4 is a cross-section of the shoe sole of FIG. 1 taken along line 4-4 in FIG. 3;

FIG. 5 is a cross-section of the shoe sole of FIG. 1 taken along line 5-5 in FIG. 3;

FIG. 6 is a cross-section of the shoe sole of FIG. 1 taken along line 6-6 in FIG. 3;

FIG. 7 is a cross-section of the shoe sole of FIG. 1 taken along line 7-7 in FIG. 3;

FIG. 8 is a top plan view of the shoe sole of FIG. 1 illustrating one embodiment of a reinforcing element suitable for use with the shoe sole of FIGS. 1-8;

FIG. 9 is a top plan view of another shoe sole illustrating another embodiment of a reinforcing element suitable for use with the shoe sole of FIGS. 1-8;

FIG. 10 is a top plan view of another shoe sole illustrating another embodiment of a reinforcing element suitable for use with the shoe sole of FIGS. 1-8;

FIG. 11 is a lateral side view of another embodiment of a shoe sole;

FIG. 12 is a bottom plan view of the shoe sole of FIG. 11;

FIG. 13 is a cross-section of the shoe sole of FIG. 11 taken along line 13-13 in FIG. 12;

FIG. 14 is a lateral side view of another embodiment of a shoe sole;

FIG. 15 is a bottom plan view of the shoe sole of FIG. 14; and

FIG. 16 is a cross-section of the shoe sole of FIG. 14 taken along line 16-16 in FIG. 15.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Referring to FIG. 1, an article of footwear shown in the form of a running shoe is indicated generally in its entirety by the reference numeral 20. The article of footwear includes a shoe sole, indicated generally by the reference numeral 100, and a shoe upper 22. The shoe sole 100 is fixed to the shoe upper 22 by suitable attachment means, such as adhesive bonding, to form the article of footwear 20. The shoe upper 22 is used to secure the article of footwear 20 and the shoe sole 100 to a wearer's foot using suitable fasteners including, for example and without limitation, shoelaces, buckles, straps, hook and loop fasteners, and any other mechanical fasteners that enable the shoe upper 22 and shoe sole 100 to be secured to a wearer's foot. In one embodiment, the shoe upper 22 is constructed from a relatively lightweight, breathable material, such as a mesh material. In other embodiments, the shoe upper 22 may be constructed from materials other than lightweight, breathable materials.

With additional reference to FIGS. 2-8, the shoe sole 100 extends in a walking or longitudinal direction 102 from a heel region 110, through a metatarsal or midfoot region 112, to a ball and toe or forefoot region 114. The heel region 110, the midfoot region 112, and the forefoot region 114 each extend in the longitudinal direction 102 over approximately one-third of the length of the shoe sole 100. The heel region 110 adjoins the midfoot region 112, and extends rearward in the longitudinal direction 102 from the midfoot region 112 to a heel 116 of the shoe sole 100. The forefoot region 114 adjoins the midfoot region 112, and extends forward in the longitudinal direction 102 from the midfoot region 112 to a toe 118 of the shoe sole 100.

As shown in FIGS. 3 and 5-7, each of the heel region 110, the midfoot region 112, and the forefoot region 114 have a respective width measured in a transverse direction 104 oriented perpendicular to the longitudinal direction 102. The sole 100 also includes a lateral side 120 and a medial side 122 disposed on transversely opposite sides of the sole 100. The lateral side 120 of the sole 100 generally refers to the outside of the sole 100 that faces outward and away from a wearer when worn on the wearer's foot, and the medial side 122 generally refers to the inner side of the sole 100 that faces towards the wearer's body when worn on the wearer's foot. The thicknesses of the sole 100 and components thereof are measured along a vertical direction 106 oriented perpendicular to both the longitudinal direction 102 and the transverse direction 104.

As shown in FIGS. 1-4, the shoe sole 100 generally includes a midsole 124 and an outsole 126. As shown in FIG. 4, the midsole 124 extends from the heel 116 of the sole 100 to the toe 118 of the sole 100, and includes an upper surface 128 for attachment to at least one of an insole (not shown) and the shoe upper 22 (FIG. 1), and a lower surface 130 disposed opposite the upper surface 128. The outsole 126 is disposed along the lower surface 130 of the midsole 124, and extends from the heel region 110 to the forefoot region 114. The outsole 126 defines a ground-contacting surface 140 of the sole 100, and is constructed from a relatively hard, abrasion-resistant material. Suitable materials from which the outsole 126 may be constructed include, for example and without limitation, hard rubber. In some embodiments, the outsole 126 is co-molded with the lower surface 130 of the midsole 124 to provide a relatively lightweight construction, and to provide a balance of wear and flexibility.

In the example embodiment, the midsole 124 has a three-piece construction including a forefoot cushioning element 132, a midfoot cushioning element 134, and a heel cushioning element 136.

The forefoot cushioning element 132 extends from the forefoot region 114 through the midfoot region 112 to the heel region 110, and defines the upper surface 128 of the midsole. In the example embodiment, the forefoot cushioning element 132 extends the entire length of the shoe sole 100 from the heel 116 to the toe 118. The forefoot cushioning element 132 adjoins the outsole 126 along the forefoot region 114 of the sole 100, and is spaced from the outsole 126 in the midfoot region 112 and heel region 110.

The forefoot cushioning element 132 extends a thickness in the vertical direction 106 in the forefoot region 114 from the upper surface 128 of the midsole 124 to the lower surface of the midsole 124. That is, the forefoot cushioning element 132 fills the entire volume of the midsole 124 in the forefoot region 114. The forefoot cushioning element 132 also includes a thin portion or segment extending from the forefoot region 114 rearward to the heel 116 of the sole 100.

The midfoot cushioning element 134 is disposed within the midfoot region 112, and adjoins the outsole 126 along the midfoot region 112. The midfoot cushioning element 134 is disposed vertically between the forefoot cushioning element 132 (specifically, the rearward extending thin segment) and the outsole 126, and horizontally between the forefoot cushioning element 132 and the heel cushioning element 136.

The heel cushioning element 136 is disposed within the heel region 110 of the sole 100 and vertically between the forefoot cushioning element 132 and the outsole 126. Moreover, the heel cushioning element 136 is disposed vertically between the midfoot cushioning element 134 and the outsole 126. The heel cushioning element 136 adjoins each of the forefoot cushioning element 132 and the outsole 126 in the heel region 110 of the sole 100.

As shown in FIG. 4, the forefoot cushioning element 132 and the heel cushioning element 136 cooperatively define a recess 138 in the midfoot region 112 of the sole 100. The midfoot cushioning element 134 is disposed within the recess 138, and vertically and horizontally between the forefoot cushioning element 132 and the heel cushioning element 136. The midfoot cushioning element 134 adjoins the forefoot cushioning element 132 along an upper surface of the midfoot cushioning element 134, and adjoins the heel cushioning element 136 along a lower surface of the midfoot cushioning element 134.

Each component of the midsole 124 is constructed from a relatively soft, flexible material as compared to the outsole 126 to provide a desired amount of damping. Suitable materials from which the components of the midsole 124 may be constructed include, for example and without limitation, polyurethane elastomer foams, open-celled foams, such as open-celled polyurethane foam, ethylene vinyl acetate (EVA), and combinations thereof. In the example embodiment, the forefoot cushioning element 132 and the heel cushioning element 136 are constructed from relatively firm materials as compared to the midfoot cushioning element 134 to provide a low to moderate level of damping and shock absorption. The midfoot cushioning element 134 is constructed from a relatively soft, elastic, and highly deformable material as compared to the forefoot cushioning element 132 and the heel cushioning element 136 to provide a high amount of damping and shock absorption. Suitable materials from which the midfoot cushioning element 134 may be constructed include, for example and without limitation, open-celled foams, such as open-celled polyurethane foam. Generally, the midfoot cushioning element 134 has a lower density and a lower hardness than each of the forefoot cushioning element 132 and the heel cushioning element 136.

In another embodiment, the heel cushioning element 136 is constructed from a relatively soft, elastic, and highly deformable material as compared to the forefoot cushioning element 132 and the midfoot cushioning element 134, and is the softest cushioning element in the midsole 124. In such embodiments, the heel cushioning element 136 has a lower density and a lower hardness than each of the forefoot cushioning element 132 and the midfoot cushioning element 134.

In the example embodiment, the forefoot cushioning element 132, the midfoot cushioning element 134, and the heel cushioning element 136 are each constructed from separate pieces of material, although in other embodiments, two or more of the forefoot cushioning element 132, the midfoot cushioning element 134, and the heel cushioning element 136 may have a monolithic or unitary construction.

As shown in FIGS. 1, 2, and 4, the shoe sole 100 has a continuously upward convex bottom profile. The bottom profile of the shoe sole 100 is sized and shaped such that an impact region 142 of the sole 100 is defined within the midfoot region 112 of the sole 100. The term “impact region” generally refers to the point or area along the ground-contacting surface 140 of the shoe sole 100 that initially strikes or contacts a ground surface during running.

The bottom profile of the shoe sole 100 curves generally upward from the midfoot region 112 to each of the heel region 110 and the forefoot region 114.

In some embodiments, the heel region 110 (specifically, the outsole 126 within the heel region 110) curves upward from the midfoot region 112 at a first radius of curvature 144 of between about 220 millimeters (mm) and about 460 mm, and, more suitably, between about 240 mm and about 350 mm. The forefoot region 114 (specifically, the outsole 126 within the forefoot region 114) curves upward from the midfoot region 112 at a second radius of curvature 146 of between about 220 mm and about 440 mm, and, more suitably, between about 240 mm and about 320 mm. The midfoot region 112 has a third radius of curvature 148 of between about 800 mm and about 1040 mm, and, more suitably, between about 840 mm and about 1000 mm. The radii of curvature of the heel region 110, the midfoot region 112, and the forefoot region 114 may vary depending on the size of the shoe and the intended application of the shoe. In some embodiments, the ratio between the radius of curvature of the heel region 110, the midfoot region 112, and the forefoot region 114 is between about 1.0:2.0:1.0 and about 1.1:3.5:1.0. In other embodiments, the heel region 110, the midfoot region 112, and the forefoot region 114 may have any suitable radii of curvature that enables the shoe sole 100 to function as described herein. In yet other embodiments, the bottom profile of the shoe sole 100 may have a single, continuous radius of curvature extending from the heel region 110, through the midfoot region 112, and into the forefoot region 114.

The bottom profile of the sole 100 results in the impact region 142 being the lowest point on the shoe sole 100 as measured in the vertical direction 106 when the sole 100 is in an unloaded condition (i.e., at rest) on a flat, reference ground plane (i.e., a plane oriented perpendicular to the vertical direction 106), indicated at 150 in FIG. 4. The condition of the shoe sole 100 illustrated in FIG. 4 is also referred to herein as a reference condition.

As shown in FIG. 4, when the shoe sole 100 is in the reference condition, the heel 116 of the sole 100 is spaced a vertical distance 152 above the impact region 142, and the toe 118 is spaced a vertical distance 154 above the impact region 142. In some embodiments, the vertical distance 152 between the heel 116 and the impact region 142 is at least about 15 mm, more suitably, at least about 25 mm, and even more suitably, at least about 35 mm. Further, in some embodiments, the vertical distance 154 between the toe 118 and the impact region 142 is at least about 25 mm, more suitably, at least about 45 mm, and even more suitably, at least about 50 mm.

The shoe sole 100 also has a thickness profile that promotes a midfoot impact region 142. Specifically, the thickness of the sole 100, measured from the upper surface 128 of the midsole 124 to the outsole 126 along a vertical axis parallel to the vertical direction 106, gradually increases from the heel region 110 to the midfoot region 112, and gradually decreases from the midfoot region 112 to the forefoot region 114. Moreover, in some embodiments (e.g., FIG. 13), the thickest portion of the sole 100 is in the midfoot region 112, and is generally aligned with the impact region 142. That is, the sole 100 has a thickness in the midsole region 112 that is greater than the thickness of the sole 100 in the heel region 110 and the forefoot region 114. The thickness of the sole 100 includes the midsole 124 and the outsole 126, and is measured from the upper surface 128 of the midsole 124 to the ground-contacting surface 140 of the sole 100 along the vertical direction 106 (i.e., a direction normal to the longitudinal direction 102 of the sole 100, and, when in the reference condition (shown in FIG. 4), normal to the ground or reference plane 150).

In one embodiment, the thickness of the sole 100 in the heel region 110 (specifically, the portion of the sole 100 that sits directly beneath the calcaneus of the foot when the sole is worn on a user's foot) is between about 13 mm and about 23 mm, and, more suitably, between about 16 mm and about 20 mm; the maximum thickness of the sole in the midfoot region 112 is between about 20 mm and about 30 mm, and, more suitably, between about 22 mm and about 26 mm; and the thickness of the sole 100 in the forefoot region 114 is between about 13 mm and about 23 mm, and, more suitably, between about 16 mm and about 20 mm.

In another embodiment, the thickness of the sole 100 in the heel region 110 (specifically, the portion of the sole 100 that sits directly beneath the calcaneus of the foot when the sole is worn on a user's foot) is between about 27 mm and about 37 mm, and, more suitably, between about 30 mm and about 34 mm; the maximum thickness of the sole in the midfoot region 112 is between about 26 mm and about 36 mm, and, more suitably, between about 28 mm and about 32 mm; and the thickness of the sole 100 in the forefoot region 114 is between about 15 mm and about 25 mm, and, more suitably, between about 17 mm and about 23 mm.

In yet another embodiment, the thickness of the sole 100 in the heel region 110 (specifically, the portion of the sole 100 that sits directly beneath the calcaneus of the foot when the sole is worn on a user's foot) is between about 31 mm and about 42 mm, and, more suitably, between about 33 mm and about 39 mm; the maximum thickness of the sole in the midfoot region 112 is between about 33 mm and about 44 mm, and, more suitably, between about 36 mm and about 41 mm; and the thickness of the sole 100 in the forefoot region 114 is between about 22 mm and about 32 mm, and, more suitably, between about 24 mm and about 30 mm. In one particular embodiment, the midfoot region 112 is between about 1 mm and about 4 mm thicker than the heel region 110 (specifically, the portion of the sole 100 that sits directly beneath the calcaneus of the foot when the sole is worn on a user's foot).

The exact thickness of the sole 100 in the heel region 110, the midfoot region 112, and the forefoot region 114 may vary depending on the size of the shoe and the intended application of the shoe. In some embodiments, the ratio between the thickness of the sole 100 in the heel region 110, the midfoot region 112, and the forefoot region 114 is between about 1.0:1.1:1.0 and about 1.0:1.7:1.0. In other embodiments, the ratio between the thickness of the sole 100 in the heel region 110, the midfoot region 112, and the forefoot region 114 is between about 1.3:1.3:1.0 and about 1.7:1.6:1.0. In yet other embodiments, the ratio between the thickness of the sole 100 in the heel region 110, the midfoot region 112, and the forefoot region 114 is between about 1.2:1.25:1.0 and about 1.4:1.5:1.0.

The bottom profile of the shoe sole 100 and, more specifically, the curvature and thickness profile of the shoe sole 100, promote a midfoot impact region. As described in more detail herein, components of the shoe sole 100 are designed to provide optimal cushioning and shock absorption, as well as promote a dynamic, rolling action during running, based on the impact region 142 being located in the midfoot region 112 of the sole 100.

The outsole 126 has a relatively stiffer construction along the midfoot region 112 to form a pivot axis 156 about which the heel region 110 and the forefoot region 114 pivot during use. In particular, the outsole 126 is relatively stiffer along the pivot axis 156 as compared to portions of the outsole 126 forward and rearward of the pivot axis 156 to provide a rigid area about which the sole 100 can pivot. The outsole 126 may be constructed from a relatively stiffer material and/or include stiffening elements, such as fibers, along the pivot axis 156 to provide an increased stiffness along the pivot axis 156. The pivot axis 156 is oriented substantially parallel to the transverse direction 104, and substantially perpendicular to the longitudinal direction 102.

As shown in FIG. 4, the pivot axis 156 is within the impact region 142 of the sole 100, and thereby facilitates a continuous gait roll from the initial point of impact to toe-off, and promotes active rolling with each step. In the example embodiment, the pivot axis 156 is located along the middle third of shoe sole 100 in the longitudinal direction 102, and, more specifically, is located at a longitudinal distance of about 40% to about 60% of the length of the shoe sole 100 from the heel 116.

The midfoot cushioning element 134 is configured to provide optimal impact absorption during running and to return energy to the user's foot as the user's weight shifts from the midfoot region 112 to the forefoot region 114. In particular, the midfoot cushioning element 134 is disposed within the midfoot region 112, and directly above (i.e., immediately adjacent to and vertically above) the impact region 142 and pivot axis 156. Moreover, the midfoot cushioning element 134 adjoins the outsole 126 along the impact region 142 of the sole such that the midfoot cushioning element 134 absorbs energy from an initial impact of the sole 100 along the impact region 142, and transfers energy to a user's foot upon the sole 100 pivoting about the pivot axis 156. Additionally, the midfoot cushioning element 134 has a thickness measured in the vertical direction 106 that gradually increases from the heel region 110 to a maximum thickness in the midfoot region 112. The midfoot cushioning element 134 thereby provides some cushioning and shock absorption in the heel region 110, while providing a majority of cushioning and shock absorption along the midfoot region 112 and impact region 142. Further, as shown in FIGS. 6 and 7, the midfoot cushioning element 134 extends in the transverse direction 104 from the lateral side 120 to the medial side 122 to provide cushioning and shock absorption across the entire width of the sole 100.

As noted above, the midsole 124 of the illustrated embodiment has a three-piece construction, including the forefoot cushioning element 132, the midfoot cushioning element 134, and the heel cushioning element 136. In some embodiments, the forefoot cushioning element 132, the midfoot cushioning element 134, and the heel cushioning element 136 have different hardness values to provide a desired hardness distribution or profile along the longitudinal direction 102 of the sole 100. In the example embodiment, the sole 100 has a tri-hardness configuration along the longitudinal direction 102 of the sole 100 that promotes a dynamic, rolling action during running, and also facilitates optimal shock absorption and energy transfer. In particular, the forefoot cushioning element 132, the heel cushioning element 136, and the midfoot cushioning element 134 have different hardness values such that the forefoot region 114 of the sole 100 has a first hardness, the heel region 110 has a second hardness less than the first hardness, and the midfoot region 112 has a third hardness that is less than both the first hardness and the second hardness. In another suitable embodiment, the forefoot cushioning element 132, the heel cushioning element 136, and the midfoot cushioning element 134 have different hardness values such that the hardness of the heel region 110 (i.e., the second hardness) is less than both the hardness of the forefoot region 114 (i.e., the first hardness) and the hardness of the midfoot region 112 (i.e., the third hardness), and the hardness of the midfoot region 112 is less than the hardness of the forefoot region 114.

In some embodiments, the forefoot cushioning element 132 has the first hardness, the heel cushioning element 136 has the second hardness, and the midfoot cushioning element 134 has the third hardness. In other embodiments, the forefoot cushioning element 132, the heel cushioning element 136, and the midfoot cushioning element 134 have different hardness values such that the resulting combination of hardness values in the forefoot region 114, the midfoot region 112, and the heel region 110 are the first hardness, the second hardness, and the third hardness, respectively.

In some embodiments, the ratio between the first hardness value in the forefoot region 114, the second hardness value in the heel region 110, and the third hardness value in the midfoot region 112 is between about 1.0:1.0:1.0 and about 2.0:1.75:1.0, and, more suitably, between about 1.2:1.1:1.0 and about 1.6:1.4:1.0. In one particular embodiment, the ratio between the first hardness value in the forefoot region 114, the second hardness value in the heel region 110, and the third hardness value in the midfoot region 112 is about 1.22:1.11:1.0. In another particular embodiment, the ratio between the first hardness value in the forefoot region 114, the second hardness value in the heel region 110, and the third hardness value in the midfoot region 112 is about 1.33:1.11:1.0.

In some embodiments, the forefoot region 114 (specifically, the forefoot cushioning element 132) has a hardness of between about 50 and 70 as measured on the Asker Type C hardness scale (hereinafter “Asker C”), and, more suitably between about 50 and 65 Asker C; the heel region 110 (specifically, the heel cushioning element 136) has a hardness of between about 40 and 60 Asker C, and, more suitably, between about 45 and 55 Asker C; and the midfoot region 112 (specifically, the midfoot cushioning element 134) has a hardness of between about 35 and 55 Asker C, and, more suitably, between about 40 and 50 Asker C. In one particular embodiment, the forefoot region 114 has a hardness of about 55 Asker C, the heel region 110 has a hardness of about 50 Asker C, and the midfoot region 112 has a hardness of about 45 Asker C. In another particular embodiment, the forefoot region 114 has a hardness of about 60 Asker C, the heel region 110 has a hardness of about 50 Asker C, and the midfoot region 112 has a hardness of about 45 Asker C.

As shown in FIG. 8, the shoe sole 100 of the illustrated embodiment also includes a reinforcing element 160 embedded within the midsole 124 (specifically, the forefoot cushioning element 132). The reinforcing element 160 is constructed from suitably rigid, elastic materials that provide both flexibility and structural support (i.e., rigidity) within the midsole 124. Suitable materials from which 160 the reinforcing element 160 may be constructed include, for example and without limitation, fiber-reinforced ethylene-vinyl acetate (EVA), carbon-fiber composites, fiber-reinforced polyurethane elastomers (TPU), glass-reinforced composites, nylon, and combinations thereof. The reinforcing element 160 may be embedded in the midsole 124, for example, by molding the midsole 124 around the reinforcing element.

In the embodiment illustrated in FIG. 8, the reinforcing element 160 has a generally u-shaped cross-section, and includes a first prong 162 and a second prong 164 connected to one another in the heel region 110 of the sole 100. Each of the first prong 162 and the second prong 164 extend in the longitudinal direction 102 from the heel region 110 to at least the midfoot region 112 to provide stiffness in the longitudinal direction 102. In the embodiment illustrated in FIG. 8, each of the first prong 162 and the second prong 164 extend in the longitudinal direction 102 from the heel region 110, through the midfoot region 112 and into the forefoot region 114.

FIG. 9 is a top plan view of another shoe sole 900 illustrating another embodiment of a reinforcing element 902 suitable for use in the shoe sole 100 of FIGS. 1-8. The reinforcing element 902 shown in FIG. 9 is substantially similar to the reinforcing element 160 shown in FIG. 8, except the reinforcing element 902 includes cross-members 904 providing stiffness in the transverse direction 104. Accordingly, like elements are labeled with like reference numerals. As shown in FIG. 9, the reinforcing element 902 includes cross-members 904 extending between and interconnecting the first prong 162 and the second prong 164. The illustrated reinforcing element 902 includes three cross-members 904, although other embodiments may include more than or less than three cross-members 904. One of the cross-members 904 is disposed in a heel region 910 of the sole 900, one of the cross-members 904 is disposed in a midfoot region 912 of the sole 900, and one of the cross-members 904 is disposed in a forefoot region 914 of the sole 900. The cross-members 904 located in the heel region 910 and the midfoot region 912 each extend in a direction parallel to the transverse direction 104, and thus provide additional stiffness in the transverse direction 104 in the heel region 910 and the midfoot region 912. The cross-member 904 located in the forefoot region 914 extends at an oblique angle of between about 25 degrees and about 40 degrees with respect to the transverse direction 104, and thus provides additional stiffness in both the longitudinal direction 102 and the transverse direction 104 in the forefoot region 914. The reinforcing element 902 shown in FIG. 9 is particularly well suited for use in a shoe sole having relatively soft heel and midfoot regions, such as the shoe sole 100 shown in FIGS. 1-8.

FIG. 10 is a top plan view of a shoe sole 1000 illustrating another embodiment of a reinforcing element 1002 suitable for use in the shoe sole 100 of FIGS. 1-8. In the embodiment illustrated in FIG. 10, the reinforcing element 1002 includes a first prong 1004 and a second prong 1006 connected to one another by a u-shaped connector 1008 in a heel region 1010 of the sole 1000. Each of the first prong 1004 and the second prong 1006 extend in the longitudinal direction 102 from the heel region 1010 to a midfoot region 1012, but do not extend into a forefoot region 1014 of the sole 1000.

The first prong 1004 is shaped complementary to a medial side 1016 of the sole 1000, and the second prong 1006 is shaped complementary to a lateral side 1018 of the sole 1000. The first prong 1004 and the second prong 1006 are spaced transversely inward from respective medial and lateral sides 1016, 1018 of the sole 1000.

The reinforcing element 1002 also includes a plurality of cross-members 1020 extending between and interconnecting the first prong 1004 and the second prong 1006. The illustrated embodiment includes four cross-members 1020, although other embodiments may include more than or less than four cross-members 1020. In the embodiment illustrated in FIG. 10, two of the cross-members 1020 extend at an oblique angle with respect to the transverse direction 104, and intersect one another approximately midway between the first prong 1004 and the second prong 1006.

The reinforcing element 1002 also includes forward projecting members 1022 that extend forward in the longitudinal direction 102 from the cross-member 1020 located at the front of the first prong 1004 and the second prong 1006. The forward projecting members 1022 are spaced transversely inward from respective medial and lateral sides 1016, 1018 of the sole 1000, and are also spaced transversely inward from the first prong 1004 and the second prong 1006. The forward projecting members 1022 thereby provide flexibility in the longitudinal direction 102 along transversely outward portions of the sole 1000 in the forefoot region 1014.

The reinforcing element 1002 also includes forefoot cross-members 1024 located in the forefoot region 1014. Each of the forefoot cross-members 1024 extend across both of the forward projecting members 1022, and beyond the forward projecting members 1022 in the transverse direction 104. The forefoot cross-members 1024 thereby provide stiffness in the transverse direction 104 along transversely outward portions of the sole 1000 in the forefoot region 1014. The illustrated embodiment includes three forefoot cross-members 1024, although other embodiments may include more than or less than three forefoot cross-members 1024.

FIGS. 11-13 are various views of another suitable embodiment of a shoe sole 1100 having a midfoot impact region. The shoe sole 1100 is substantially identical to the shoe sole 100 shown in FIGS. 1-8, except for dimensional variations. Accordingly, like elements are labeled with like reference numerals.

The shoe sole 1100 illustrated in FIGS. 11-13 has a more pronounced midfoot region 112 as compared to the sole 100 of FIGS. 1-8. For example, the heel region 110 (specifically, the outsole 126 within the heel region 110) of the shoe sole 1100 curves upward from the midfoot region 112 at a first radius of curvature 144 less than the first radius of curvature 144 of the shoe sole 100 of FIGS. 1-8, and the forefoot region 114 (specifically, the outsole 126 within the forefoot region 114) curves upward from the midfoot region 112 at a second radius of curvature 146 less than the second radius of curvature 146 of the shoe sole 100 of FIGS. 1-8.

Additionally, in the embodiment illustrated in FIGS. 11-13, the thickness of the sole 1100 in the heel region 110 is between about 17 mm and about 27 mm, and, more suitably, between about 20 mm and about 24 mm. The maximum thickness of the sole 1100 in the midfoot region 112 is between about 33 mm and about 44 mm, and, more suitably, between about 36 mm and about 41 mm. The thickness of the sole 1100 in the forefoot region 114 is between about 10 mm and about 20 mm, and, more suitably, between about 13 mm and about 17 mm. The ratio between the thickness of the sole 1100 in the heel region 110, the midfoot region 112, and the forefoot region 114 is between about 1.4:2.5:1.0 and about 1.5:2.6:1.0.

FIGS. 14-16 are various views of another suitable embodiment of a shoe sole 1400 having a midfoot impact region. The shoe sole 1400 extends in a walking or longitudinal direction 1402 from a heel region 1410, through a midfoot region 1412, to a forefoot region 1414.

The shoe sole 1400 illustrated in FIGS. 14-16 includes a midsole 1416 and an outsole 1418. As shown in FIG. 16, the midsole 1416 includes an upper surface 1420 for attachment to at least one of an insole and a shoe upper, and a lower surface 1422 disposed opposite the upper surface 1420. The outsole 1418 is disposed along the lower surface 1422 of the midsole 1416, and extends from the heel region 1410 to the forefoot region 1414.

In the embodiment illustrated in FIGS. 14-16, the midsole 1416 has a unitary construction. That is, the midsole 1416 of the shoe sole 1400 is not formed from separate parts or components. Moreover, in the embodiment illustrated in FIGS. 14-16, the midsole 1416 does not include a separate cushioning element. That is, the midsole 1416 is free of separate cushioning elements, although the midsole 1416 may act as a cushioning element depending on the hardness of the midsole 1416.

Similar to the shoe sole of FIGS. 1-8, the shoe sole 1400 has a continuously upward convex bottom profile such that an impact region 1424 of the sole 1400 is defined within the midfoot region 1412 of the sole 1400.

In the embodiment illustrated in FIGS. 14-16, the heel region 1410 (specifically, the outsole 1418 within the heel region 1410) curves upward from the midfoot region 1412 at a first radius of curvature 1426 of between about 390 mm and about 450 mm, the forefoot region 1414 (specifically, the outsole 1418 within the forefoot region 1414) curves upward from the midfoot region 1412 at a second radius of curvature 1428 of between about 360 mm and about 420 mm, and the midfoot region 1412 has a third radius of curvature 1430 of between about 970 mm and about 1030 mm.

Additionally, the outsole 1418 has a relatively stiffer construction along the midfoot region 1412 to form a pivot axis 1432 about which the heel region 1410 and the forefoot region 1414 pivot during use. In particular, the outsole 1418 is relatively stiffer along the pivot axis 1432 as compared to portions of the outsole 1418 forward and rearward of the pivot axis 1432 to provide a rigid area about which the sole 1400 can pivot. The outsole 1418 may be constructed from a relatively stiffer material and/or include stiffening elements, such as fibers, along the pivot axis 1432 to provide an increased stiffness along the pivot axis 1432. The pivot axis 1432 is oriented substantially parallel to a transverse direction 1404 of the sole 1400 (FIG. 15), and substantially perpendicular to the longitudinal direction 1402. As shown in FIG. 16, the pivot axis 1432 is within the impact region 1424 of the sole 1400, and thereby facilitates a continuous gait roll from the initial point of impact to toe-off, and promotes active rolling with each step.

Embodiments of the shoe soles described are particularly well suited for running, and provide several advantages over known running shoe soles. For example, embodiments of the shoes soles described herein have a bottom profile that is contoured and shaped to promote an impact or strike point along the midfoot region of the sole, rather than the heel region. Moreover, the shoe soles described herein are generally convex, and curve upward from the midfoot region to each of the heel and forefoot regions. The shoe soles thereby promote a dynamic, rolling action during running as a user's weight shifts from the heel region to the forefoot region. Additionally, the shoe soles described herein include a midfoot pivot axis disposed along the impact region of the sole, thereby promoting a continuous gait roll from the initial strike or impact point to toe-off. Moreover, the shoe soles described herein include a relatively thick cushioning element arranged in the midfoot region of the sole directly above the impact region of the sole. The shoe soles thereby provide enhanced cushioning and a soft landing with excellent shock absorption during midfoot strike as compared to running shoes having an impact region or cushioning element in the heel region of the sole. Further, the shoe soles described herein also have a three-piece construction and provide a tri-hardness configuration that promotes a dynamic, rolling action during running, and also facilitates optimal shock absorption and energy transfer.

When introducing elements of the present invention or the embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 

What is claimed is:
 1. A shoe sole for an article of footwear, the sole extending in a longitudinal direction from a heel region, through a midfoot region, to a forefoot region, the sole comprising: a midsole having an upper surface for attachment to at least one of an insole and a shoe upper, and a lower surface disposed opposite the upper surface, the midsole including a forefoot cushioning element, a midfoot cushioning element, and a heel cushioning element; and an outsole disposed along the lower surface of the midsole and defining a ground-contacting surface of the sole; wherein the sole has an upwardly convex bottom profile such that an impact region of the sole is defined within the midfoot region, the midfoot cushioning element disposed within the midfoot region and directly above the impact region of the sole.
 2. The shoe sole of claim 1, wherein the outsole has a relatively stiff construction along the midfoot region thereby forming a pivot axis within the impact region about which the heel region and the forefoot region pivot, the midfoot cushioning element disposed directly above the pivot axis.
 3. The shoe sole of claim 2, wherein the midfoot cushioning element adjoins the outsole along the impact region of the sole, whereby the midfoot cushioning element is configured to absorb energy from an initial impact of the sole along the impact region and transfer energy to a user's foot upon the sole pivoting about the pivot axis
 4. The shoe sole of claim 1, wherein the forefoot cushioning element and the heel cushioning element cooperatively define a recess in the midfoot region of the sole, the midfoot cushioning element disposed within the recess and vertically and horizontally between the forefoot cushioning element and the heel cushioning element.
 5. The shoe sole of claim 1, wherein the forefoot cushioning element extends a thickness in the forefoot region from the upper surface of the midsole to the lower surface of the midsole, the forefoot cushioning element adjoining the outsole along the forefoot region of the sole and extending from the forefoot region to the heel region.
 6. The shoe sole of claim 5, wherein the heel cushioning element is disposed vertically between the forefoot cushioning element and the outsole, the heel cushioning element adjoining each of the forefoot cushioning element and the outsole in the heel region of the sole.
 7. The shoe sole of claim 1, wherein the midfoot cushioning element has a hardness less than a hardness of each of the forefoot cushioning element and the heel cushioning element.
 8. The shoe sole of claim 7, wherein the midfoot cushioning element has a first hardness, the forefoot cushioning element has a second hardness greater than the first hardnesss, and the heel cushioning element has a third hardness less than the second hardness.
 9. The shoe sole of claim 1, wherein the midfoot cushioning element has a first hardness, the forefoot cushioning element has a second hardness greater than the first hardnesss, and the heel cushioning element has a third hardness less than both the first hardness and the second hardness.
 10. The shoe sole of claim 1, wherein the shoe sole includes a lateral side and an opposing medial side, the midfoot cushioning element extending from the lateral side to the medial side.
 11. The shoe sole of claim 1, further comprising a reinforcing element embedded in the midsole, the reinforcing element having a generally u-shaped cross-section and including a first prong and a second prong connected to one another in the heel region of the sole, each of the first prong and the second prong extending in the longitudinal direction from the heel region to at least the midfoot region to provide stiffness in the longitudinal direction.
 12. An article of footwear comprising the shoe sole of claim 1 and an upper secured to the midsole.
 13. A shoe sole for an article of footwear, the sole extending in a longitudinal direction from a heel region, through a midfoot region, to a forefoot region, the sole comprising: a midsole having an upper surface for attachment to at least one of an insole and a shoe upper, and a lower surface disposed opposite the upper surface, the midsole including a forefoot cushioning element, a midfoot cushioning element, and a heel cushioning element; and an outsole disposed along the lower surface of the midsole and defining a ground-contacting surface of the sole; wherein the sole has an upwardly convex bottom profile such that an impact region of the sole is defined within the midfoot region, the midsole having a first hardness in the forefoot region, a second hardness in the heel region less than the first hardness, and a third hardness in the midfoot region above the impact region less than both the first hardness and the second hardness.
 14. The shoe sole of claim 13, wherein the outsole has a relatively stiff construction along the midfoot region to form a pivot axis within the impact region about which the heel region and the forefoot region pivot.
 15. The shoe sole of claim 13, wherein the forefoot cushioning element has the first hardness, the heel cushioning element has the second hardness, and the midfoot cushioning element has the third hardness.
 16. The shoe sole of claim 15, wherein the forefoot cushioning element and the heel cushioning element cooperatively define a recess in which the midfoot cushioning element is disposed, the forefoot cushioning element extending from the forefoot region to the heel region.
 17. The shoe sole of claim 15, wherein the midfoot cushioning element has a hardness of between about 35 Asker C and about 55 Asker C.
 18. The shoe sole of claim 13, wherein a ratio between the first hardness, the second hardness, and the third hardness is between about 1.0:1.0:1.0 and about 2.0:1.75:1.0.
 19. The shoe sole of claim 18, wherein the ratio between the first hardness, the second hardness, and the third hardness is between about 1.2:1.1:1.0 and about 1.6:1.4:1.0.
 20. A shoe sole for an article of footwear, the sole extending in a longitudinal direction from a heel region, through a midfoot region, to a forefoot region, the sole comprising: a midsole having an upper surface for attachment to at least one of an insole and a shoe upper, and a lower surface disposed opposite the upper surface, an outsole disposed along the lower surface of the midsole and defining a ground-contacting surface of the sole wherein the sole has an upwardly convex bottom profile such that an impact region of the sole is defined within the midfoot region, the outsole having a relatively stiff construction along the midfoot region to form a pivot axis within the impact region about which the heel region and the forefoot region pivot, wherein the heel region curves upward from the midfoot region and has a radius of curvature of between 390 millimeters and about 450 millimeters, and the forefoot region extends upward from the midfoot region and has a radius of curvature of between 360 millimeters and about 420 millimeters. 